Effects of uniaxial pressure on the spin ice Ho2Ti2O7

TL;DR

This study investigates how applying uniaxial pressure affects the magnetic properties of the spin ice material Ho2Ti2O7, combining experimental magnetization measurements with an extended dipolar spin ice model to predict phase transitions.

Contribution

The paper extends the dipolar spin ice model to include uniaxial pressure effects and validates it with magnetization and neutron scattering measurements, revealing pressure-induced magnetic phase changes.

Findings

Good model fit for pressures along two crystalline directions

Prediction of ferromagnetic transition above 3.3 GPa

Inclusion of susceptibility-dependent demagnetizing factors

Abstract

The spin ice materials Ho2Ti2O7 and Dy2Ti2O7 are experimental and theoretical exemplars of highly frustrated magnetic materials. However, the effects of an applied uniaxial pressure are not well studied, and here we report magnetization measurements of Ho2Ti2O7 under uniaxial pressure applied in the [001], [111] and [110] crystalline directions. The basic features are captured by an extension of the dipolar spin ice model. We find a good match between our model and measurements with pressures applied along two of the three directions, and extend the framework to discuss the influence of crystal misalignment for the third direction. The parameters determined from the magnetization measurements reproduce neutron scattering measurements we perform under uniaxial pressure applied along the [110] crystalline direction. In the detailed analysis we include the recently verified susceptibility dependence of the demagnetizing factor. Our work demonstrates the application of a moderate applied pressure to modify the magnetic interaction parameters. The knowledge can be used to predict critical pressures needed to induce new phases and transitions in frustrated materials, and in the case of Ho2Ti2O7 we expect a transition to a ferromagnetic ground state for uniaxial pressures above 3.3 GPa.